> Every little factor of 25 performance increase really helps.> > Ramback is a new virtual device with the ability to back a ramdisk> by a real disk, obtaining the performance level of a ramdisk but with> the data durability of a hard disk. To work this magic, ramback needs> a little help from a UPS. In a typical test, ramback reduced a 25> second file operation[1] to under one second including sync. Even> greater gains are possible for seek-intensive applications.

What about doing a similar thing as a device mapper target? Have a look a dm-cache, I know that development of that has stopped but it doesn't mean it couldn't be ressurected. It has an advantage that it is generic (any two block devices will do) and you don't need to populate the "cache" on start-up - it happens automatically through cache misses.

Another use could be a flash based disk accelerator which may be pretty popular nowadays.